afs600 Actel Corporation, afs600 Datasheet - Page 61

• Manufacturer Part Number: afs600
• Description: Actel Fusion Programmable System Chips Mixed-signal Family With Optional Arm Support
• Manufacturer: Actel Corporation

Read Next Operation
The Read Next operation is a feature by which the next
block relative to the block in the Block Buffer is read
from the FB Array while performing reads from the Block
Buffer. The goal is to minimize wait states during
consecutive sequential Read operations.
The
predetermined manner because it does look-ahead
reads. The general look-ahead function is as follows:
Figure 2-39 • Read Next Waveform (Non-Pipe Mode, 32-bit access)
Figure 2-40 • Read Next WaveForm (Pipe Mode, 32-bit access)
• Within a page, the next block fetched will be the
• When reading the last data block of a page, it will
• When reading spare pages, it will read the first
DATAWIDTH[1:0]
ADDR[17:0]
STATUS[1:0]
READNEXT
Read
next in linear address.
fetch the first block of the next page.
block of the next sector's spare page.
RD[31:0]
STATUS[1:0]
ADDR[17:0]
READNEXT
BUSY
RD[31:0]
REN
CLK
Next
BUSY
REN
CLK
operation
0
0
0
A0
A0
is
performed
A1
A1
in
A d v an c ed v1 . 4
D0
S0
a
D1
S1
S0
D0
When an address on the ADDR input does not agree
with the predetermined look-ahead address, there is a
time penalty for this access. The FB will be busy finishing
the current look-ahead read before it can start the next
read. The worst case is a total of nine BUSY cycles before
data is delivered.
The Non-Pipe Mode and Pipe Mode waveforms for Read
Next operations are illustrated in
Figure
A2
D2
S2
• Reads of the last sector will wrap around to sector 0.
• Reads of Auxiliary blocks will read the next linear
D1
S1
A3
A2
page's Auxiliary block.
2-40.
D3
S3
D2
S2
A4
A3
0
0
S3
D3
Actel Fusion Programmable System Chips
A4
A5
D4
S4
0
0
D5
S5
A6
A5
S4
D4
S6
D6
A7
S5
D5
D7
S7
A6
A8
D6
S6
Figure 2-39
0
0
A7
S7
D7
A9
S8
D8
A8
S9
D9
0
0
2-47
and